WO2021043636A1 - Piezoelectric stick-slip-motor and method of controlling same - Google Patents
Piezoelectric stick-slip-motor and method of controlling same Download PDFInfo
- Publication number
- WO2021043636A1 WO2021043636A1 PCT/EP2020/073749 EP2020073749W WO2021043636A1 WO 2021043636 A1 WO2021043636 A1 WO 2021043636A1 EP 2020073749 W EP2020073749 W EP 2020073749W WO 2021043636 A1 WO2021043636 A1 WO 2021043636A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- drive voltage
- phase
- motor
- voltage
- voltage signal
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 32
- 230000001965 increasing effect Effects 0.000 claims abstract description 26
- 230000003247 decreasing effect Effects 0.000 claims abstract description 20
- 125000004122 cyclic group Chemical group 0.000 claims abstract description 9
- 238000004904 shortening Methods 0.000 claims description 7
- 230000000051 modifying effect Effects 0.000 claims description 3
- 230000007423 decrease Effects 0.000 abstract description 5
- 230000001133 acceleration Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 2
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- QHGVXILFMXYDRS-UHFFFAOYSA-N pyraclofos Chemical group C1=C(OP(=O)(OCC)SCCC)C=NN1C1=CC=C(Cl)C=C1 QHGVXILFMXYDRS-UHFFFAOYSA-N 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/02—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing linear motion, e.g. actuators; Linear positioners ; Linear motors
- H02N2/06—Drive circuits; Control arrangements or methods
- H02N2/062—Small signal circuits; Means for controlling position or derived quantities, e.g. for removing hysteresis
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/02—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing linear motion, e.g. actuators; Linear positioners ; Linear motors
- H02N2/021—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing linear motion, e.g. actuators; Linear positioners ; Linear motors using intermittent driving, e.g. step motors, piezoleg motors
- H02N2/025—Inertial sliding motors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/02—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing linear motion, e.g. actuators; Linear positioners ; Linear motors
- H02N2/06—Drive circuits; Control arrangements or methods
Definitions
- the present invention relates to a piezoelectric stick-slip-motor and method of controlling same.
- Piezoelectric stick-slip-motors are known e.g. from US 2015/0076965, WO 2018/134637 A1 or EP 3 120449 B1.
- a piezoelectric actuator element is charged with a periodic voltage, in particular a high-frequency sawtooth voltage.
- the high-frequency expan sion and contraction of the actuator element effected by the voltage is transmitted, via a friction element arranged on said actuator element, to a friction body such that the friction body is moved during a deflection of the actuator element in a stick phase, in which static friction exists between the friction element and the friction body, whereas, in a slip phase, sliding friction exists between the friction element and the friction body, such that the friction body is not driven along, or is driven along only to a very minor extent, by the movement of the friction element.
- the acceleration or the movement speed of the actuator element is in this case configured such that, owing to the forces that act in the frictional contact between the friction element and friction body, there is no resulting sliding friction or only negligible resulting sliding friction, such that the friction body is in any case driven along by the friction element as a result.
- the acceleration or movement speed of the actuator element is so high that the forces in the frictional contact between friction element and friction body are no longer sufficient for the friction element to drive the friction body along, and, owing to the inertia of the friction body, a relative movement between the friction element and friction body (that is to say sliding) occurs.
- Fig. 1 shows two cycles of a typical cyclic stick-slip driving signal accord ing to the state of the art in a diagram of voltage over time, wherein phase 1 represents the Move or Stick phase, phase 2 represents the Pause after move, phase 3 represents the Slip phase and phase 4 represents the Pause after slip.
- Vb is the base voltage
- Vp is the peak voltage
- dV/dt is the gradient of increasing the drive voltage from the base voltage Vb to the peak voltage Vp in phase 1 of the cycle C.
- Phase 3 (“Slip phase”) needs to be as short as possible (typically ⁇ 2 ps) and phases 2 and 4 (“Pause after move” and “Pause after slip”) are typically between 3 and 10 ps. Pause times too short or too long negatively affect the efficiency of the motor, resulting in a slight reduction of speed.
- the effective speed of the motor is mainly determined by the frequency of the signal and the peak voltage. Since phases 2 (“Pause after move”), 3 (“Slip phase”) and 4 (“Pause after slip”) are relatively constant, the frequency of the signal is determined mainly by the duration of the move phase.
- the peak voltage Vp is kept constant and the motor speed is controlled by the frequency of the signal. In doing so, during acceleration, deceleration and low velocities, the piezo motor has to operate at lower, audible frequencies. This causes the stick-slip motor and thus the motion device to generate an audible noise. During closed loop, this noise can be particularly disturbing to the user as the servo loop constantly changes fre quency to compensate for the varying following error.
- Some controllers try to avoid the noise generation by operating only at a high frequency, typi cally 20 kHz. This method though does not allow for acceleration, deceleration or lower speeds, a major limitation. But, when operating in closed loop, the frequency still has to change and this frequency modulation still generates a disturbing sound.
- the method of controlling a piezoelectric stick-slip-motor according to claim 1 comprises the following steps:
- Step A applying to the motor a cyclic sawtooth-waveform drive voltage signal with a constant frequency in which the drive voltage increases to and decreases from a peak voltage for oper ating the motor with a constant speed;
- Step B changing the motor speed by gradually increasing or decreasing the gradient of in creasing the drive voltage to the peak voltage with each subsequent sawtooth-waveform drive voltage signal cycle while keeping the frequency of the drive voltage signal constant.
- each sawtooth-waveform drive voltage signal cycle in Step A comprises the following phases: a first phase representing a stick (move) phase in which the drive voltage increases from a base voltage to the peak voltage, a second phase representing a pause after the first phase in which the drive voltage is maintained at the peak voltage, a third phase representing a slip phase in which the drive voltage decreases from the peak voltage to the base voltage, wherein preferably the third phase lasts 2 ps or less, and a fourth phase representing a pause after the third phase in which the drive voltage is maintained at the base voltage, wherein preferably the fourth phase lasts between 3 and 10 ps.
- Such drive voltage signal cycle is pertinent for operating piezoelectric stick-slip motors.
- Step B it may improve the operation characteristics of the piezoelectric stick-slip motor if Step B in cludes gradually increasing or decreasing the peak voltage for each subsequent drive voltage signal cycle, preferably until the peak voltage passes a threshold voltage level at which the motor starts or stops operating, respectively.
- Step B By gradually decreasing the gradient of increas ing the drive voltage to the peak voltage with each subsequent sawtooth-waveform drive volt age signal cycle, the motor can be smoothly decelerated and stopped.
- gradually increasing the gradient of increasing the drive voltage to the peak voltage with each subsequent sawtooth- waveform drive voltage signal cycle the motor can be smoothly started and accelerated.
- the claimed method includes keeping the gradient of increasing and/or the gradient of decreasing the drive voltage between the base voltage and the peak voltage constant within each drive voltage signal cycle in Step A and/or Step B.
- Step B includes at least one of the following sub-steps of mod ifying the sawtooth-waveform drive voltage signal as compared to Step A:
- Step B1 gradually decreasing the gradient of increasing the drive voltage to the peak voltage with each subsequent sawtooth-waveform drive voltage signal cycle while maintaining the peak voltage constant so as to extend the first phase while shortening the second phase to the same amount for compensating the extension of first phase.
- Sub-Step B2 gradually decreasing the peak voltage as well as the gradient of increasing the drive voltage to the peak voltage with each subsequent sawtooth-waveform drive voltage sig nal cycle so as to extend the first phase while eliminating the second phase and possibly short ening the third phase for compensating the extension of first phase.
- step B1 the reduction of the gradient of increasing the drive voltage to the peak voltage takes place by extending phase 1 without a reduction of the peak voltage, wherein the exten sion of phase 1 is compensated by shortening phase 2 to the same amount.
- step B2 phase 1 is extended to become longer than phases 1 and 2 of Step A in combination, so that the phase 2 is completely skipped and phase 3 directly follows on phase 1.
- the claimed method includes keeping the gradient of decreasing the drive voltage from the peak voltage to the base voltage constant for each subsequent drive voltage signal cycle in Step A and/or Step B.
- the claimed method includes maintaining the time period of the fourth phase constant for each subsequent drive voltage signal cycle in Step A and/or Step B.
- the claimed method includes maintaining the base voltage constant for each subsequent drive voltage signal cycle in Step A and/or Step B.
- the speed control and positional precision of the piezoelectric stick-slip motor may be im proved if the claimed method includes operating the motor in closed loop and/or in servo loop.
- a piezoelectric stick-slip-motor comprising an ele ment to be driven and a stator, said stator having a friction element, a controller and at least one piezoelectric actuator that is configured to deform upon application of a drive voltage signal from the controller so as to impart a movement to the friction element in order to drive the element to be driven by stick-slip-contact, wherein the controller is configured to perform the method according to one of the preceding claims.
- Fig. 1 shows the shape of a typical stick-slip sawtooth-waveform drive voltage signal through out two consecutive drive voltage signal cycles.
- Fig. 2 shows a diagram indicating the relation between the peak voltage and speed, according to which the speed is not directly proportional with the peak voltage. Below a certain peak voltage value, the motor will stop generating a motion. The relationship between the peak voltage and speed cannot be accurately defined.
- Fig. 3 shows the shape of a stick-slip sawtooth-waveform drive voltage signal according to the claimed invention, wherein phases 3 (“Slip phase”) and 4 (“Pause after slip”) remain relatively constant while phase 2 (“Pause after move”) is being absorbed by phase 1 (“Move phase”).
- the loss of phase 2 (“Pause after move”) causes a reduction of the motor efficiency which adds to the desired reduction of speed.
- a piezoelectric stick-slip-motor comprises an element to be driven and a stator, said stator having a friction element, a controller and at least one pie zoelectric actuator that is configured to deform upon application of a drive voltage signal from the controller so as to impart a movement to the friction element in order to drive the element to be driven by stick-slip-contact.
- the controller is configured to perform the method according to one of the appended claims, as will be described below.
- the claimed method basically enables speed variation of the piezoelectric stick-slip-motor while eliminating the noise generation by keeping the motor driving signal at a constant high frequency and varying the peak voltage of the signal.
- the method includes the following steps:
- Step A applying to the motor a cyclic sawtooth-waveform drive voltage signal with a constant frequency in which the drive voltage V increases to and decreases from a peak voltage Vp for operating the motor with a constant speed;
- Step B changing the motor speed by gradually increasing or decreasing the gradient dV/dt of increasing the drive voltage V to the peak voltage Vp with each subsequent sawtooth-wave- form drive voltage signal cycle C while keeping the frequency of the drive voltage signal con stant.
- the motor is preferably controlled in closed loop, wherein the servo loop changes the peak voltage with high resolution in real time, at the servo clock rate.
- the gradient dV/dt of increasing the drive voltage V to the peak voltage Vp is gradually increased such that it is greater in a second drive voltage signal cycle C as compared to a first drive voltage signal cycle C, and greater in a third drive voltage signal cycle C as compared to the second drive voltage signal cycle C.
- the gradient dV/dt of increasing the drive voltage V to the peak voltage Vp is gradually decreased such that it is smaller in a second drive voltage signal cycle C as compared to a first drive voltage signal cycle C, and smaller in a third drive voltage signal cycle C as compared to the second drive voltage signal cycle C.
- the sawtooth-waveform drive voltage signal cycle C in Step A comprises: a first phase 1 representing a stick/move phase in which the drive voltage V increases from a base voltage Vb to the peak voltage Vb, a second phase 2 representing a pause after the first phase 1 in which the drive voltage V is maintained at the peak voltage Vp, a third phase 3 representing a slip phase in which the drive voltage V decreases from the peak voltage Vp to the base voltage Vb, and a fourth phase 4 representing a pause after the third phase 3 in which the drive voltage V is maintained at the base voltage Vb.
- the cyclic sawtooth-waveform drive voltage signal is typically applied to the motor 1 with a constant frequency of 20 kHz or more.
- the third phase 3 lasts 2 ps or less, wherein the fourth phase 4 lasts between 3 and 10 ps.
- Step B particularly includes the following sub-steps of mod ifying the sawtooth-waveform drive voltage signal as compared to Step A:
- Sub-Step B1 gradually decreasing the gradient dV/dt of increasing the drive voltage V to the peak voltage Vp with each subsequent sawtooth-waveform drive voltage signal cycle C while maintaining the peak voltage Vp constant so as to extend the first phase 1 while shortening the second phase 2 to the same amount for compensating the extension of first phase 1.
- the gradient dV/dt in phase 1 of a Step B cycle is less than the gradient dV/dt in phase 1 of a Step A cycle.
- the peak voltage VpB1 of the first cycle in step B is the same as the peak voltage VpA in Step A.
- Sub-Step B2 gradually decreasing the peak voltage Vp as well as the gradient dV/dt of in creasing the drive voltage V to the peak voltage Vp with each subsequent sawtooth-waveform drive voltage signal cycle C so as to extend the first phase 1 while eliminating the second phase 2 and shortening the third phase 3 for compensating the extension of first phase 1.
- the gradient dV/dt in phase 1 and peak voltage VpB2 of the second cycle in step B are less than the gradient dV/dt in phase 1 and the peak voltage VpB1 of the first cycle in step B, respectively.
- the gradients dV/dt in phase 1 as well as the peak voltages VpB3, VpB4 and VpB5 are gradually decreasing with each subsequent sawtooth-waveform drive voltage signal cycle C until the peak voltage VpB5 (underpasses a threshold voltage level Vt at which the motor 1 stops operating.
- the peak voltage Vp as well as the gradient dV/dt of increasing the drive voltage V to the peak voltage Vp are changed from one sawtooth-waveform drive voltage signal cycle C to another.
- the gradient dV/dt of increasing the drive voltage V from the base voltage Vp to the peak voltage Vb and the gradient dV/dt of decreasing the drive voltage V from the peak voltage Vp to the base voltage Vb are constant.
- the base voltage Vb and the time period of the fourth phase 4 are constant for each subsequent drive voltage signal cycle in Step A and Step B.
- the motor speed is not directly proportional with the peak voltage. Below a certain Peak voltage value, the motor will stop generating a motion. The relationship between the two cannot be accurately defined.
- Step B phase 3 (“Slip phase”) and phase 4 (“Pause after slip”) remain relatively constant while phase 2 (“Pause after move”) is being absorbed by phase 1 (“Move phase”).
- phase 2 Phase after move
- the loss of the phase 2 (“Pause after move”) causes a reduction of the motor efficiency, which adds to the desired reduction of speed.
Landscapes
- General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
Abstract
Description
Claims
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2022514746A JP2022547898A (en) | 2019-09-06 | 2020-08-25 | Piezo stick slip motor and its control method |
CN202080062338.3A CN114930708A (en) | 2019-09-06 | 2020-08-25 | Piezoelectric stick-slip motor and control method thereof |
EP20760464.6A EP4026240B1 (en) | 2019-09-06 | 2020-08-25 | Piezoelectric stick-slip-motor and method of controlling same |
KR1020227011256A KR20220057602A (en) | 2019-09-06 | 2020-08-25 | Piezoelectric stick-slip-motor and its control method |
US17/640,142 US11888415B2 (en) | 2019-09-06 | 2020-08-25 | Piezoelectric stick-slip-motor and method of controlling same |
ES20760464T ES2960213T3 (en) | 2019-09-06 | 2020-08-25 | Piezoelectric stick-slip motor and method to control it |
JP2023183273A JP2024001258A (en) | 2019-09-06 | 2023-10-25 | Piezoelectric stick slip motor and control method thereof |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19195819.8A EP3790183A1 (en) | 2019-09-06 | 2019-09-06 | Piezoelectric stick-slip-motor and method of controlling same |
EP19195819.8 | 2019-09-06 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2021043636A1 true WO2021043636A1 (en) | 2021-03-11 |
Family
ID=67909273
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2020/073749 WO2021043636A1 (en) | 2019-09-06 | 2020-08-25 | Piezoelectric stick-slip-motor and method of controlling same |
Country Status (7)
Country | Link |
---|---|
US (1) | US11888415B2 (en) |
EP (2) | EP3790183A1 (en) |
JP (2) | JP2022547898A (en) |
KR (1) | KR20220057602A (en) |
CN (1) | CN114930708A (en) |
ES (1) | ES2960213T3 (en) |
WO (1) | WO2021043636A1 (en) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6545389B1 (en) * | 1997-06-02 | 2003-04-08 | Minolta Co., Ltd. | Driving control apparatus and driving control method |
US6703762B1 (en) * | 1998-12-17 | 2004-03-09 | Minolta Co., Ltd. | Actuator and driving apparatus thereof |
US20150076965A1 (en) | 2013-09-13 | 2015-03-19 | Physik Instrumente (PI) GmbH & Co., KG | Compact versatile stick-slip piezoelectric motor |
WO2017137044A1 (en) * | 2016-02-11 | 2017-08-17 | Physik Instrumente (Pi) Gmbh & Co. Kg | Method and device for actuating an electromechanical element |
EP3120449B1 (en) | 2014-03-21 | 2018-05-09 | Physik Instrumente (PI) GmbH & Co. KG | Inertial drive |
WO2018134637A1 (en) | 2017-01-18 | 2018-07-26 | Physik Instrumente (Pi) Gmbh & Co. Kg | Stick-slip piezoelectric motor |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11103583A (en) * | 1997-09-26 | 1999-04-13 | Minolta Co Ltd | Drive unit using electro-mechanical converter and drive pulse generator adapted to its drive |
JP3609927B2 (en) | 1997-11-06 | 2005-01-12 | コニカミノルタホールディングス株式会社 | Drive device |
JPH11289780A (en) * | 1998-03-31 | 1999-10-19 | Minolta Co Ltd | Driver using electromechanical converting element |
JP4495274B2 (en) * | 1999-07-09 | 2010-06-30 | Hoya株式会社 | Ultrasonic motor drive control device |
JP2002095272A (en) * | 2000-09-11 | 2002-03-29 | Minolta Co Ltd | Driver |
US7061745B2 (en) * | 2004-09-24 | 2006-06-13 | Varian, Inc. | Variable capacitor adjustable by linear motor |
US8593033B2 (en) * | 2009-06-11 | 2013-11-26 | Micronix Usa | Multi-element, stick-slip piezo motor |
EP3435535A1 (en) | 2017-07-25 | 2019-01-30 | Physik Instrumente (PI) GmbH & Co. Kg | Method for closed-loop motion control of an ultrasonic motor |
-
2019
- 2019-09-06 EP EP19195819.8A patent/EP3790183A1/en not_active Withdrawn
-
2020
- 2020-08-25 KR KR1020227011256A patent/KR20220057602A/en not_active Application Discontinuation
- 2020-08-25 US US17/640,142 patent/US11888415B2/en active Active
- 2020-08-25 JP JP2022514746A patent/JP2022547898A/en active Pending
- 2020-08-25 EP EP20760464.6A patent/EP4026240B1/en active Active
- 2020-08-25 ES ES20760464T patent/ES2960213T3/en active Active
- 2020-08-25 WO PCT/EP2020/073749 patent/WO2021043636A1/en unknown
- 2020-08-25 CN CN202080062338.3A patent/CN114930708A/en active Pending
-
2023
- 2023-10-25 JP JP2023183273A patent/JP2024001258A/en active Pending
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6545389B1 (en) * | 1997-06-02 | 2003-04-08 | Minolta Co., Ltd. | Driving control apparatus and driving control method |
US6703762B1 (en) * | 1998-12-17 | 2004-03-09 | Minolta Co., Ltd. | Actuator and driving apparatus thereof |
US20150076965A1 (en) | 2013-09-13 | 2015-03-19 | Physik Instrumente (PI) GmbH & Co., KG | Compact versatile stick-slip piezoelectric motor |
EP3120449B1 (en) | 2014-03-21 | 2018-05-09 | Physik Instrumente (PI) GmbH & Co. KG | Inertial drive |
WO2017137044A1 (en) * | 2016-02-11 | 2017-08-17 | Physik Instrumente (Pi) Gmbh & Co. Kg | Method and device for actuating an electromechanical element |
WO2018134637A1 (en) | 2017-01-18 | 2018-07-26 | Physik Instrumente (Pi) Gmbh & Co. Kg | Stick-slip piezoelectric motor |
Also Published As
Publication number | Publication date |
---|---|
ES2960213T3 (en) | 2024-03-01 |
JP2024001258A (en) | 2024-01-09 |
KR20220057602A (en) | 2022-05-09 |
CN114930708A (en) | 2022-08-19 |
US20220321030A1 (en) | 2022-10-06 |
EP3790183A1 (en) | 2021-03-10 |
EP4026240B1 (en) | 2023-09-27 |
EP4026240A1 (en) | 2022-07-13 |
US11888415B2 (en) | 2024-01-30 |
JP2022547898A (en) | 2022-11-16 |
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